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91.
In this paper, we study the hyperkähler metric and practise GMN’s construction of hyperkähler metric on focus–focus fibrations. We explicitly compute the action–angle coordinates on the local model of focus–focus fibrations, and show its semi-global invariant should be harmonic to admit a compatible holomorphic 2-form. Then we study the canonical semi-flat metric on it. After the instanton correction, finally we are able to get a reconstruction of the generalized Ooguri–Vafa metric. 相似文献
92.
《Journal of Saudi Chemical Society》2020,24(10):765-776
A series of new 1,4-pentadien-3-one derivatives containing 1,2,4-triazole moiety were synthesized. The structures of the synthesized compounds were charactered via 1H NMR, 13C NMR and HRMS. Antibacterial bioassays indicated that some of compounds showed potential antibacterial activities against Ralstonia solanacearum (Rs), Xanthomonas oryzae pv. Oryzae (Xoo) and Xanthomonas axonopodis pv. Citri (Xac). Compounds F8 and F17 showed good in vitro antibacterial activities against Rs, with the EC50 values of 18.6 and 18.6 μg/mL, respectively, which were better than commercial agent bismerthiazol (55.2 μg/mL). Furthermore, compounds F12 and F15 showed good in vitro antibacterial activities against Xoo, with the EC50 values of 10.9 and 17.5 μg/mL, which were better than commercial agent bismerthiazol (69.3 μg/mL). Moreover, compounds F2, F9, F16 and F17 showed good in vitro antibacterial activities against Xac, with the EC50 values of 6.6, 5.4, 7.5 and 7.8 μg/mL, respectively, which were better than commercial agent bismerthiazol (54.9 μg/mL). The effect of compound F9 on Xac bacterial cell membrane rupture was observed by scanning electron microscopy (SEM). In addition, antiviral bioassays indicated that some of compounds showed excellent protection activities against tobacco mosaic virus (TMV). Compounds F5 and F15 showed good protecting activity against TMV, with the EC50 values of 108.3 and 105.4 μg/mL, respectively, which were better than commercial agent ningnanmycin (214.7 μg/mL). Microscale thermophoresis (MST) also showed that the binding of compound F2 to TMV coat protein (TMV-CP) yielded a Kd value of 1.260 ± 0.654 μmol/L, which was very close to ningnanmycin (1.058 ± 0.286 μmol/L). Similarly, the molecular docking studies for F2 and F5 with TMV-CP (PDB code: 1EI7, ID: 4QGH) indicated that compounds F2 and F5 had partially interacted with TMV-CP. 相似文献
93.
《Arabian Journal of Chemistry》2020,13(2):3690-3701
In the present study, different extracts of stem bark of Shorea tumbuggaia and roots of Syzygium alternifolium were screened for total phenolic content (TPC), total flavonoid content (TFC) and in vitro DPPH radical scavenging activity to isolate the natural antioxidants. The bioassay-guided fraction of stem bark of Shorea tumbuggaia yielded three compounds, piceatannol (ST-1), resveratrol-12-C-β-d-glucopyranoside (ST-2) and hopeaphenol (ST-3). Similarly, a systematic phytochemical examination of extracts of Syzygium alternifolium roots had resulted five compounds, 5,7,8,5′-tetramethoxy-3′,4′-methylenedioxyflavone (SA-1), 5-hydroxy-4′,7-dimethoxy-6,8-di-C-methylflavone (SA-2), quercetin 7-methylether (SA-3), kaempferol 7,4′-dimethylether 3-O-β-d-glucopyranoside (SA-4) and taxifolin 3-O-α-l-rhamnopyranoside (SA-5). Structures of the isolates were established using UV, IR, Mass, 1H and 13C NMR spectral studies. Density Functional Theory (DFT) calculations, Molecular docking and Lipinski rule of five were conducted to explored the antioxidant activity of isolated compounds. SA-3 (37.52 µg/mL) and ST-1 (42.43 µg/mL) showed highest IC50 values compared to the Ascorbic acid (45.97 µg/mL) and have highest electron affinities (EA eV) along with smallest HOMO-LUMO energy gap. Molecular docking and binding affinity studies with NADPH and SPSB2 proteins, revealed the prominent antioxidant activity of SA-3 and ST-1 with molecular interaction besides promising solvation energies. Hence, the two compounds maybe useful for the treatment of oxidative damage related diseases. 相似文献
94.
95.
The role of the primary P3+ functionality in the phosphite overall stabilization performance was re-evaluated. Tris(2,4-di-t-Bu-phenyl)phosphite (P-1) and its oxidation product tris(2,4-di-t-Bu-phenyl)phosphate (P-1ox) were tested both alone and in the presence of hindered phenol during processing in polypropylene. Efficiencies were quantified using the processing degradation index (PDI). The position of the traditional multiple extrusion curve was determined by a single parameter, describing the degree of polymer degradation. Its reciprocal allowed calculating formulations relative efficiencies. It was shown that oxidation of P3+ into P5+ is responsible for 75 % phosphite stabilization performance, regardless phosphite acts alone or in combination with phenol. If P3+ is completely oxidized, stabilizer still works. For the residual performance, the reactions of 2,4-di-t-Bu-phenyl substituents (secondary structure), are responsible. Besides processing, reactions of P3+ also contribute to the long-term stability at 150 °C. Once phosphite is oxidized, the secondary structure does not contribute to the long-term stability at all. 相似文献
96.
Evgeny Korotyaev 《Journal of Differential Equations》2006,223(2):229-260
Consider the Hill operator Ty=-y″+q(t)y in L2(R), where the real potential q is 1-periodic and q,q′∈L2(0,1). The spectrum of T consists of spectral bands separated by gaps γn,n?1 with length |γn|?0. We obtain two-sided estimates of the gap lengths ∑n2|γn|2 in terms of . Moreover, we obtain the similar two-sided estimates for spectral data (the height of the corresponding slit on the quasimomentum domain, action variables for the KdV equation and so on). In order prove this result we use the analysis of a conformal mapping corresponding to quasimomentum of the Hill operator. That makes it possible to reformulate the problems for the differential operator as the problems of the conformal mapping theory. Then the proof is based on the analysis of the conformal mapping, the embedding theorems and the identities. Furthermore, we obtain the similar two-sided estimates for potentials which have p?2 derivatives. 相似文献
97.
ZHU Na LI Xu-wen LIU Gui-ying SHI Xiao-lei GUI Ming-yu SUN Chang-qing JIN Yong-ri College of Chemistry Jilin University Changchun P. R. China 《高等学校化学研究》2009,(3)
A new chalcone glycoside,butein-4-methoxyl-4'-O-(6-O-acetyl)-β-D-glucopyranoside(2),along with seven known compounds,namely,quercitrin(1),luteolin-7-O-β-D-glucopyranoside(3),butein-4'-O-β-D-glucopyra-noside(4),butein-4-methoxyl-4'-O-β-D-glucopyranoside(5),butin-7-O-β-D-glucopyranoside(6),isoquercitrin(7),and sulfurein(8) was isolated from aerial parts of Bidens ceruna L. Their structures were elucidated on the basis of spectroscopic studies. Compounds 1―8 were tested for their DPPH radical scavenging activi... 相似文献
98.
99.
E. Gozzi 《Physics letters. A》2018,382(16):1075-1077
In this paper we derive various identities involving the action functional which enters the path-integral formulation of quantum mechanics. They provide some kind of generalisations of the Ehrenfest theorem giving correlations between powers of the action and its functional derivatives. 相似文献
100.
以系列1.0、2.0代树状聚酰胺-胺(PAMAM)为桥联基,3-(3,5-二叔丁基-4-羟基苯基)丙酰氯为抗氧化基团,通过酰胺化缩合反应合成了系列树状桥联受阻酚类抗氧化剂。红外光谱和核磁共振氢谱证实了系列树状聚酰胺-胺桥联受阻酚类抗氧化剂的化学结构。采用EPR技术研究系列树状聚酰胺-胺桥联受阻酚类抗氧化剂清除DPPH·的能力,结果表明,系列树状聚酰胺-胺桥联受阻酚类抗氧化剂具有良好清除DPPH·活性,且随着清除时间的延长、桥联基长度和代数的增加,其清除活性增强。 相似文献